Sink bowls made from stainless steel provide excellent durability in comparison to some other materials. Stainless steel sinks are often used in harsh environments to resist damage and in sterile environments. Stainless steel sink bowls are also commonly used for aesthetic reasons to compliment certain kitchen designs.
Methods for deep drawing a seamless sink bowl from one-piece of stainless steel sheet, as well as such sink bowls, are generally known in the art. Stainless steel sink bowls formed by deep drawing have heretofore been limited to smooth sidewalls based on the deep drawing process required to form the bowl. Methods are also known for producing two adjacent sink bowls in a single seamless stainless steel sheet. Generally, such methods for forming single or double bowl sinks involve clamping a stainless steel blank in a double action press. The blank is clamped between upper and lower gripping members, and the bowl is formed in one or more draws by applying a force to a forming die which contacts the clamped blank and forces it through a drawing die. For single deep drawn sink bowls, more than one draw is often required, and partially formed bowls are often stock-piled between the first and subsequent forming steps. Double bowl sinks require a number of drawing steps and the partially formed blanks are also stock-piled between forming steps.
Sink bowls made from cast ceramic, iron, polymeric or other materials are also known in the art. Such sink bowls are generally molded from various materials in liquid form and cured or fired to form the finished sink bowl. A greater variety of shapes and sizes of sink bowls can be made by this method in comparison with forming stainless steel. One such sink bowl, which is manufactured by the assignee of the present application, includes a ledge located at a medial portion of the sidewall of the sink bowl. While this ledge, which is generally used for supporting a wire rack or grid above the bottom of the sink, is easily formed in cast sink bowls, forming such a ledge at a medial portion of a seamless stainless steel sink bowl drawn from a single blank was not thought to be possible. This is due to a number of factors, such as the location of the ledge at a medial position on the sidewall, the depth of draw required, formation of the ledge in less than all sides of the bowl, and the tangential displacement of the sidewall required in forming the ledge which generally leads to wrinkles or puckers resulting in non-usable product.